Character display unit



. associated with that aperture.

United States Patent O CHARACTER DISPLAY UNIT Joseph T. McNaney, La Mesa, Calif., assignor to General Dynamics Corporation, Rochester, N.Y., a corporaton of Delaware Application April 2, 1957, Serial No.'650,Z1`5 7. Claims. (CI. 315-21) This invention relates to high-speed message'display systems and, more particularly, to an improved arrangement for converting electrical data at high speed nto displays which can be read.

There are a consderable number of diiferent messagedisplay systems presently being employed. These range all the way from the slow speed electromagnetically operated letter or number at a time-selecting-and-displaying apparatus to high-speed cathode-ray tube apparatus of the type described and claimed in a patent issued to ths inventor, No. 2,76l,988, called Cathode-Ray Apparatus. This cathode-ray apparatus provides a special type of cathode-ray tube wherein means are provided for shaping an electron beam into the form of a character or number, which is then allowed to impinge upon the screen of the tube to become visible. There is a need for a message-display system having a speed on the order of that provided by the cathode-ray tube apparatus, which, however, does not require a continual regeneration for its preservation. Cathode-ray tube presentations do require a continual or a recurring application of message information in order that a message be kept on display.

One of the objects of this invention is the provision of a high-speed message display system in which once symbols are displayed they are maintained for any desred period of time without the requirement of rewriting or regeneration.

Another object of this invention is the provision of methods-display apparatus wherein illuminated message characters ranging in size from a lfraction of an inch to several inches in height may be displayed in arrangements consisting of one to several hundred different characters.

Yet another object of this invention is the provision of a novel, useful, and simple high-speed message display system.

These and other objects of this invention are provided in a system wheren a plurality of character-projection units are employed. Each of these units includes a viewing screen for viewing the characters or message displayed. opposite the viewing screen is a light-aperture plate, or lens system, having a plurality of lenses, each of which is associated with and opposite a charactershaped aperture. The character-shaped apertures are in a light mask spaced from the light-aperture plate. A light source is provided for each of the character-shaped apertures with means for selecting a desred charactershaped aperture by selectively exciting the light source The lens system operates to superimpose any one of the characters selected upon substantially the same area of the viewing screen.

The light source includes a plurality of different light cavities, a character-shaped aperture being at one end of the light cavity. The other end of the plurality of cavities is a translucent envelope having therein an illuminating gas and a plurality of pairs of electrodes. Each pair of electrodes is positioned adjacent a light cavity. Potentials are applied to these electrodes which-have a value just below the ignition point of the illuminatin -appended claims.

gas. of electrodes, and means are provided for applyng the potential selectively to these ignition electrodes to cause the gas between the desred ones of the associated pair of electrodes to become illuminated.

The novel features that are considered characteristic of this invention are set forth with particularityin the The invention itself, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description when read in conrays on the viewing screen.

lenses or pinhole apertures in the plate 12 are related to nection with the accompanying drawings, in which:

Figurel is an isometric drawing of a display element of the invention;

Figure 2 shows a light mask suitable for use invention;

Figure 3 is an enlarged sectional View along lines 3-3 of Figure l; i i

Figure 4 is an enlarged. View in section of an arrangement for selecting an aperture-shaped character, in aci cordance with this invention;` V

Figure 5 shows a circuit diagram for securing selective illumination' in accordance with this invention; and

Figure 6 'shows a desred arrangement for an embodi- I i ment of the invention; Reference is uow'madeto Figure l, which shows an isometric drawing of a display element of the invention.`

This includes a viewing screen 10, upon which a selected character will be projected. A light-apertureplate,or lenssystem, 12 includes a plurality of'lenses, one for each character' to be projected on the Viewing screen; These lenses may be either a glass or a plastic lens, .or' Spaced from the lens' system is a light' mask 14, which comprises, as shown in Figure 2, a plate having a plurality of character-shaped may preferably be a pinhole lens.

order to illuminate a desred one of the character apertures, which-is then projected on the same area of the screen. a in The entire system may be Conveniently packaged within walls 20 defining a rectangular box, so that a plurality of these display elements may be mounted to arrange,

for message displays whereby any desred message can be provided. V

Figure 3 shows a View in section `and enlarged along the lnes 3-3 of Figure l. This View includes the por- 'tion of the invention between the light mask and the viewing screen. Light rays which pass through the character-shaped apertures 15 in the Symbol mask '14 are dire cted through pinhole apertures 11 in the plate 12L These pinhole apertures act as lenses and focus the light the space and size dimension of the character-shaped apertures and the distance from the viewing screen 10', so that regardless of which; one of the character-shaped apertures is illuminatcd, the characterwill be displayed on substantially the same area of the viewing screen 10.

The walls 22, which extend between the aperture mask or plate` 14 and the lens plate 12 dene a light cavity. These walls prevent light scatter by preventing light from an .illuminated. charaeter-shaped aperture from going Patented Feb. s, 1960 An ignition electrode is associated with each pair with this;

The placement of thesethrough any other lens or pinhole than the one with which t is associated. The technique of using a plurality of lenses to focus light emanating from one of a plurality of dierent sources upon substant'ally the same area of a viewing screen is well known and will not, be. described in further detail here.

Reference is now made to Figure 4, which shows an enlarged section of one of the arrangements which may be employed for selectively illuminating an apertureshaped character. It includes an evacuated envelope 30, which is filled with a suitable illuminating gas, such as neon, and in which there is supported pairs of spaced electrodes 32, 34. These pairs of electrodes 32, 34 are positioned to be opposite a character-shaped aperture 15 -in the masking plate 14, which is positoned* adjacent the wall of the envelope 30. There means are provided, as shown in Figure 5, for basing each of the electrodes 32, 34 just below the potential required to ionize the gas between them. A third ignition electrode 33 is positioned between an associated pair of electrodes 32, 34. The ignition electrodes 33 extend outside of the envelope 30.

In operation, in order to select the illuminaton for a desired character-shaped aperture a potential is applied to the ignition electrode 33, which is associated with the pair of spaced electrodes which are positioned adjacent the desired character-shaped aperture. The potential applied to the electrode 33 should be more positive than that existing between the two electrodes associated therewith. This will cause the gas to glow between the pair of electrodes associated with the ignition electrode upon which the more positive potential is applied. Although light rays resulting from the gas glow will radiate in all directions, the principal light source is opposite the desired character-shaped aperture and the walls 22 assist in eliminating substantially all but the desired light rays. The Outline of the character-shaped aperture which is illuminated will be focused on the viewing screen through the pinhole aperture 11.

Any suitable means for applying the positive potential to the extending ignition electrodes may be employed. This may be achieved by using either manual switches or their electronic counterparts, such as gate tubes or ip-flop circuits for selectively applying potentials to the desired ones of the extending ignition electrodes in accordance with input or control signals applied to their circuits.

Referring to Fgure 5, there is shown a preferred arrangement for selecting a desired one of the ignition electrodes 33. In Figure 5, there may be seen a circuit diagram of such arrangement, which includes cathoderay tube means 40. This cathode-ray tube means has the ignition electrodes 33 extending through its envelope at a location which normally is reserved for the screen of the tube. These ignition electrodes thus are positioned as targets for the electron beam 42. The electronbean generator comprises well-known structure including the cathode 44 and focusing electrode 46, in which there is an intensity control grid 48. Intensity of the beam is controlled by signals applied to this grid from an intensity control signal source 49. Horizontal defiecting plates 50 and vertical deflecting plates 52 are employed to direct the electron beam 42 in response to signals from a deection-control signal source 51 on any desired one .of the ignition electrodes 33. Beam centering is performed in well-known manner using horizontal and vertical centering Controls, respectively 53, 55. An accelerating electrode 57 is employed, which may be the well-known aquadag coating on the inner surface of the envelope of the cathode-ray tube.

Bias for the entire system is derived from a potential source across which a voltage-dropping resistor 54 is connected. The accelerator electrode 57 is connected to the most positive point 56 of the resistor 54. Electrodes 34 are connected through a switch 58 to a point 601011 the voltage-divding resistor 54, which is more 4,;l negative than the point 56. Electrodes 32 are connected to a point 62 on the voltage-dropping resistor 54, which is more negative than point 60. The potential between points 60 and 62 is selected to provide a potential on the electrode point which is just below the excitation point of the gas contained in the envelope 30. The beam-focusing electrodes ariddeflection electrodes are also connected to derive the required Operating potentials i from the voltage-dropping resistor 54.

Due to the potential difi'erence provided: between the, points 60 and 62, the relationship` of an, ignition; electrode potential to a given pair of electrodes with which it is associated is such; that ionization will take place between such ignition electrode and an adjacent electrode 34 and also between the electrode 34 and the opposite electrode of the pair 32 when an electron beam 42 is directed upon the ignition electrode 33. After the beam 42 is cut off by the intensity control grid 48, ionization will still continue between the selected pair of electrodes which maintainsthe illuminaton of a character upon the viewing screen. By means of the switch 58,' contact may be broken, whereby the potential applied' between the two electrodes is interrupted. This way, the illuminaton may be extinguished. It will be understoodthat switch 58 is merely exemplary of any suitable means whereby such potential interruption may be made to occur, including electron tube circuitsttransistor circuits, and` the like. It should be noted that the accelerator 57 serves. the purpose of bringing the potential of the electron beam` 42 up to the potential of the` accelerator, which is equal to the task of igniting the glow between the electrodes 32 and 34 by virtue of the latter's connectons to th Power supply.

A preferred package for the invention is shown in Figure 6. Although not necessary, the cathode-ray tube` is contained in a somewhat rectangular form to, enable compact message arrays. In order to provide` a high` degree of flexibility and to permit manufacturing, ecen: omy, as well as inexpensive. servicing the ignition elec-` trodes 33 can consist of two parts. One part extends through the envelope 30 and terminates ina socket which, can mate with pins which comprise the other partand which extend through the. target end of the cathodezray tube. Thus, whenever a cathode-ray tube burns. outit may be replaced very readily.

Any number of the units described andshown may be, assembled to display and retain. messages made of, letters, numerals, and special symbols., The beam in eachunt, may be separately controlled from. suitable selectionsig nals to provide any message desired. It should also be appreciated that other meansor controlling` the electron beams than the ones shown may be employedwhich are still within the scope of this invention. For example, in place of the usual heater cathode and deflection electrode arrangement, a photo cathode can be employed and selection of the location forignition electrodes upon, which the electron beam will fall can be made by, a hole in a card or paper tape through which lightcan be al: lowed to fall upon the portion of photovcathode to` cause it to provide the required electron beam on an oppositely located ignition electrode.

There has accordingly been shown a novel; and useful message-display system whichcan Convert at relatively` high speeds any electrical data into displays of alpha-.

numeric symbols. These symbolswill remaindisplayed on the viewing screens for any desired period ot times.

The apparatus shown also has the advantage of lending;

itself to the construction ofdisplays of-any desired, size I claim:

l. A high-speed message display system comprising ag,

masking plate having a. plurality of different; charactershaped apertures, a viewing screen on; one side of'said plate, and means for selectively illumnating said ape tures on the other side of' said plate, said selcctive illuminaton means including anevacuatedvesehan illumnatq.

ing gas filling said vessel, a plurality of spaced pairs of electrodes each pair of which is positioned in said vessel to be opposite one of the character-shaped apertures in said plate, means for applying potentials to said spaced electrodes which are just below the ignition point of said illuminating gas, and means for igniting the illuminating gas between selected ones of said pairs of electrodes to selectively illuminate said character-shaped apertures.

2. A high-speed message display system comprising a masking plate having a plurality of difierent charactershaped apertures, a viewing screen on one side of said plate, and means for selectively illuminating said apertures on the other side of said plate, said selective illumination means including an evacuated vessel, an illuminating gas filling said vessel, a plurality of spaced pairs of electrodes each pair of which is positioned in said vessel to be opposite one of the character-shaped apertures in said plate, means for applying potentials to said spaced electrodes which are just below the ignition point of said illuminating gas, a separate ignition electrode positioned proximal to and associated with a different one of said spaced pairs of electrodes, and means for applying an ignition potential to selected ones of said ignition electrodes to cause said illuminating gas to glow between the associated pairs of electrodes.

3. A high-speed message display system as recited in claim 2 wherein said means for applying an ignition potential to selected ones of said ignition electrodes includes eathode-ray beam generating apparatus and means to defiect the cathode-ray beam generated by said apparatus to impinge upon selected ones of said ignition electrodes.

4. A -sgh-speed message display system comprising a masking plate having a plurality of different charactershaped apertures, a viewing screen on one side of said plate, and means for selectively illuminating said apertures on the other side of said plate, said selective illumination means including an evacuated vessel, an illuminating gas filling said vessel, a plurality of spaced pairs of electrodes each pair of which is positioned in said vessel to be opposite one of the cha-racter-shaped apertures, means for applyng potentials to said spaced electrodes which are just below the ignition point of said illuminating gas, a separate ignition elect'ode positioned proximal to and associated with a different one of said spaced pairs of electrodes, a cathode-ray tube having beamgenerating means at one end and said ignition electrodes extending into the other end as targets, and means for defiecting the beam generated by said means to impinge upon desired ones of said ignition electrodes to cause 6 said illuminating of electrodes.

5. A high-speed message display system as recited in claim 4 wherein there is interposed between said masking plate and said viewing screen lens means for focusing thelight passing through selected character apertures onto said screen, and means between said plate and said lens means for preventing the scattering of light from said apertures.

6. A high-speed message display system as recitedin claim 5 wherein said lens means includes a lens board having a plurality of pinhole apertures positioned therein to focus the light passing through selected apertures on a desredarea of said screen, each of said pinhole apertures being associated with one of said character-shaped apertures; and the means for preventing scattering of the light from said apertures includes a pluralty of walls spacng said lens board from said character-shaped aperture plate and being positioned to prevent the light from a character-shaped aperture from passing through other than the associated pinhole aperture.

7. A high speed message display system comprising: a masking plate having a pluralty of different charactershaped apertures; a viewing screen on one side of said plate; means on the other side of said plate for selectively illuminating said apertures, said selective illuminating means including an evacuated vessel, an illuminating gas filling said vessel, a spaced pair of electrodes positioned in said vessel opposite individual said character-shaped apertures in said plate, means for applying to said spaced electrodes potentials that are just below the 'ignition point of said illuminating gas, and means for igniting the illuminating gas between said pair of electrodes to illuminate said individual character shaped aperture whereby the light from said illuminated gas traverses said individual selected aperture and forms on said viewing screen a lighted pattern whose configuration corresponds with the shape of said selected aperture.

References Cited in the file of this patent UNITED STATES PATENTS 1,779,748 Nicolson Oct. 28, 1930 l,810,692 Wald June 16, 1931 2,021,010 Jenkns Nov. '12, 1935 2,049,763 DeForest Aug. 4, 1936 2,283,383 McNaney May 19, 1942 2,3 13,286 Okolicsanyi Mar. 9, 1943 2,591,729 Seaman Apr. 8, 1952 2,608, 674 Depp Aug. 26, 1952 2,749,480 Ruderfer' Junes, 1956 gas to glow between the associated pairs 

